dpkg-shlibdeps: analyze in priority the shlibs of the current package

dpkg-shlibdeps: analyze in priority the shlibs of the current package

When looking for a dependency, consider the shlibs of the current package
before the shlibs of other binary packages of the same source. This is
important when a library is built in multiple flavors and each version comes
with a different dependency for the same library.